As a conventional pipe joint for a compressor of a car air-conditioner and the like, as shown in FIG. 12, it is known that a pipe joint comprising a connected hose 2 for supplying refrigerant, and a flange 20, having a communication passage 26 communicates through into the hose 2, is fixedly joined to a block 3 wherein the flange 20 is fixedly joined to the block of a compressor by using one bolt 30.
In a pipe joint 1′ of this kind, a rubber made O-ring 70 is provided at an outer circumference of a protrusion portion 25 of the flange 20′ which is joined to a connection opening 3a of the block 3. By the O-ring 70, a connecting portion of the communication passage 26 and the connection opening 3a is sealed to an external portion.
In the meantime, in recent years, as refrigerant for a car air-conditioner, carbon dioxide gas (CO2) is noted instead of chlorofluorocarbon gas. In case that the carbon dioxide gas is used as refrigerant, compared with chlorofluorocarbon gas, a pressure of gas flowing in the pipe joint 1′ becomes 10 times higher or so, there is a problem that the gas leaks through the O-ring 70.
Consequently, as a method for eliminating such the gas leakage, it is considered to use a metal seal instead of the O-ring. However, in case that the metal seal is used, for fixing the metal seal, it is necessary to press in parallel by a large tightening force using more than two bolts which deteriorates fixing operation. As a result, a number of man-hour increases compared from the conventionally known pipe joint 1′.